The way I see it, without getting into the prevailing connotations of "hacking" versus "cracking," quantum computing only strengthens wire security (data in motion), by preventing interception, since observation results in tamper evidence. Meaning that the new level of "quantum" security relies heavily on dedicated isolation between the transmitter and the receiver. This part only reveals that a copy of the enciphered message may have been captured by someone eavesdropping on the signal.

It doesn't mean an enemy couldn't simply deny service by knocking out the satellite, or try to capture information via a side channel by sneaking into a peripheral system's firmware, but it means when bouncing a "beam" off a satellite, the signal might enjoy totally private transmission, end-to-end, or show that someone noticed the message, and may try to decode it, indicating compromised information and a possible loss of surprise or hazard of enemy awareness.

As for unbreakable codes (data at rest), I'm pretty sure most military protocols lean heavily on one-time pads. I'd very honestly guess that prime number ciphers and the like are, well, probably secretly flimsy, and intended for civilian consumers to chase their tails over, while celebrity security bros widely endorse them as a means of cashing in on smart phone apps or book deals.

A lot of the quantum secrecy technology is buzz-wordified as "teleportation entanglement space foam time travel" or whatever, by journalists, but here's an old article I was able to quickly Google:

https://qz.com/760804/chinas-new-quantum-satellite-will-try-...